US Bridges

MT-43 FH 20 over Trail Creek

Fair

Beaverhead County, Montana · 12M W Wisdom · Structure no. P00046014+01231

Built
1961
64 years old
Condition
Fair
inspected August 2023
Type
Slab
Concrete Continuous
Length
60 ft
3 main spans
Daily traffic
461
2023 count
Owner
State
State Highway Agency

About this bridge

MT-43 FH 20 over Trail Creek is a concrete continuous slab carrying MT-43 FH 20 over Trail Creek in Beaverhead County, Montana. It was built in 1961, so it is 64 years old, older than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 461 vehicles a day, roughly 11% of them trucks, projected to reach 484 by 2043. The structure is 60 ft (18.3 m) long and 31 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesMT-43 FH 20
CrossesTrail Creek
Location12M W Wisdom
RouteState Highway 43
CountyBeaverhead County
StateMontana
Coordinates45.64278, -113.69222
Functional classRural Minor Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating31 US tons
Inventory rating24 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length60 ft (18.3 m)
Longest span22 ft (6.7 m)
Deck width31 ft (9.5 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic461 (2023)
Projected traffic484 by 2043
Trucks11%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was MT-43 FH 20 over Trail Creek built?

It was built in 1961, making it 64 years old in 2025.

What condition is MT-43 FH 20 over Trail Creek in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in August 2023.

How much traffic does MT-43 FH 20 over Trail Creek carry?

About 461 vehicles per day (2023 count), of which roughly 11% are trucks.

How long is MT-43 FH 20 over Trail Creek?

The structure is 60 ft (18.3 m) long with a longest span of 22 ft (6.7 m) and a deck 31 ft wide.

Who owns MT-43 FH 20 over Trail Creek?

It is owned by the State Highway Agency.